Curing epoxidized diene polymers with hydrazine and carbon disulfide



2,876,214 Patented Mar. 3, 1959 CURING EPOXIDIZED DIENEPOLYMERS WITHHYDRAZINE AND CARBON DISULFIDE Charles E. Wheelock and Boris -'Franzus,Bartlesville,

kla., assignors to Phillips Petroleum Company, a .corporation ofDelaware No Drawing. Application September 30, 1957 Serial No. 686,859

l0rClaims. (Cl.26079.5)

This invention relates to thermosetting resins prepared from epoxidizedliquid diene polymers. In copending applications, Serial No. 612,890,filedSeptember 28, 1956, and Serial No. 626,286, filed December 5, 1956,epoxidized diene polymers have been described. These epoxy compounds,are those wherein an oxygen atom bridges adjacent carbon atoms, saidcarbon atoms being joined by a single valence bond. It is furtherdisclosed therein that these polymers are useful as resins for varyinguses such as laminating, casting, and coating compositions. We have nowdiscovered another curing system for epoxidized polymers of this type.

The following are objects of our invention.

An object of this invention is to provide thermosetting resins. Afurther object of this invention is to provide an improved curing systemfor epoxidized liquid polybutadiene.

Other objects and advantages of this invention will become apparent toone skilled in the art'upon-reading th accompanying disclosure.

The present invention relates to a thermosetting resin comprising amixture of an epoxidized polymer containing 0.08 to 0.8 epoxy groups peraliphatic double bond originally present in the polymer and, based upon100 parts of said epoxidized polymer, 1 to 8, preferably 3 to 6 parts ofhydrazine and approximately 2 mols of carbon disulfide per mol of saidhydrazine.

When the resinsare prepared from homopolymers of butadiene, the productsare characterized in that the original unsaturated portion of themolecule is converted by the epoxidation reaction to units of which (1)8 to 70 percent, preferably 13 to 50 percent, of said units .areselected from the group consisting of 0 GH2C OHCHr- (2) up to 82percent, preferably '50 to 77 percent, of said units are selected fromthe group consisting of RO-CHz RO-CH -1H-CH2- and OR OR OHz-CH-( ]HOHzwhere R is selected from the group consisting of H and H CR1 R being analkyl, aryl, alkaryhor aralkyl group of one to 20 carbon atoms, and (3')10 to 35 percent of said units are selected from the group consistingofand Of course, the present invention is not limited to these polymersbut includes polymers, including copolymers, of dienes containing 4 to 6carbonatoms. Furthermore, other monomers can be used in preparingthecopolymers such as styrene, substituted styrene, vinyl ethyl ether,acrylonitrile, methacrylonitrile, .ethyl acrylate, and the like.

The liquid polymers can be prepared by any suitable method for preparingthese including the use of sufficient amounts of mercaptan modifiersinemulsion polymerization systems to produce liquid polymers and by masspolymerization using finely dividedalkali metal catalysts. Aparticularly preferred method is that described in Crouch 2,631,175. Theproducts, following epoxidation, are preferably liquidshaving .aviscosity up to 500,000 centipoises within the temperature. range 0 to100 C.

.It is this epoxidized polymer which we cure with hydrazine and carbondisulfide. -As stated, we prefer .to use 1 to 8 parts of the hydrazine.and approximately 2 mols of the carbon disulfide ,permol of thehydrazine. However, 1 to 10 mols of carbon disulfide can be used-per-mol ofhydrazine and 1.5 to -3 mols-onthe'same basis constitutes apreferred range. In some cases we also use a cure rate accelerator suchas diethylene triamine in an amount up to .6 parts by weight per '100parts of the epoxidized liquid polymer. Other basic materials can beused in .place of this triamine such as pyridine or quinoline andinorganic bases such as calcium oxide, calcium hydroxide, and the alkalimetal hydroxides.

'In preparing the thermosetting resin we mix the hydrazine and carbondisulfide with the epoxidized polymer and 'heat the mixture within therange of 20 to 300 C. for a time to give the desired hardness. The timeof cure is dependent upon the temperature used, higher temperaturesproducing a more rapid cure. Usually a cure time of ,10 to 100 hours :isvused. Obviously, fillers, pigments, and the like can be incorporated inthe mixture at thesame time.

The following example sets forth specific embodiment of resins preparedaccording to the process of our invention.

Example Liquid polybutadiene, prepared according to the method of Crouch2,631,175 and having a viscosity of about 1500 Saybolt Furol seconds atF. and an unsaturation of 80 percent of theoretical, e. g., 0.8 doublebonds per C unit, was stripped in a batch operation by flushing for 45minutes with nitrogen at a temperature of 190 to 200 C. and at apressure of 10 to 20 mm. Hg absolute. This polymer was epoxidized bydissolving 432 grams of the polymer in two liters of chloroform to whichwas added 280 grams of a nuclear sulfonated ion exchange resin(Amberlite IR-) in the acid form and 35 mls. of glacial acetic acid. Thetemperature was 43 C. To this mixture there was added 266 grams of 50percent hydrogen peroxide over a period of 30 to 40 minutes whilemaintaining the temperature at 43 C. The mixture agents being present.

was stirred for 2.5 hours at this temperature. Then 500 milliliters ofwater were added, the aqueous phase was removed, and the polymericproduct washed several times with dilute aqueous sodium bicarbonate andthen with water. The neutral organic phase was dried over anhydroussodium sulfate and the solvent was stripped by warming under vacuum.

The thus prepared epoxidized polymer was then analyzed for epoxy oxygencontent and total oxygen content. Epoxy oxygen content was determined bythe hydrochloric acid-dioxane. method given in Organic Analysis,Mitchell et al., volume 1, pages 135-136, Interscience Publishers,

Inc., New York (1953). Total oxygen content was deter- 1 mined bypyrolyzing the sample in an atmosphere of nitrogen, converting theoxygen compounds formed to carbon monoxide by passage of the gases overcarbon at a temperature of 1120" C., passing the gases through a liquidnitrogen trap to remove interfering substances,

oxidizing the carbon'monoxide to carbon dioxide by means of copper oxidekept at a temperature of 300 C., collecting the resulting carbon dioxidein a liquid nitrogen trap, and, after pumping out the residual gases bymeans of a vacuum pump, determining the carbon dioxide manometrically ina standard volume.

Several batches of the polymer were prepared according to the abovemethod and blended. Analysis of this blend showed it to contain 5.4percent by weight of oxirane oxygen and a total oxygen content of 9.3percent on the same basis. Assuming that all of the oxygen was presentas. either epoxy oxygen or hydroxyl oxygen,

it was calculated that the epoxidized polymer contained 0.251 epoxygroups per double bond originally present in the liquid polybutadiene.Portions of this epoxidized material were mixed with hydrazine'andcarbon disulfide and the resins were cured. Diethylene triamine was alsousedin certain runs. The amounts of each of the components and theproperties of the cured products are shown in the following table:

For comparison, a portion of the epoxidized liquid polybutadiene washeated at 100 C. without any curing A time of 77 hours was requiredbefore a ShoreD hardness of 5 was obtained. Comparison of this resultwith run 1 in the above table shows that'a Shore D hardness of 5 wasobtained in only 16.5

hours using the hydrazine and the carbon disulfide. All

of the other runs gave harder products.

As many possible embodiments can be made of this invention withoutdeparting from the scope thereof, it is to be understood that all matterherein set forth is to be interpreted as illustrative and not as undulylimiting the invention.

We claim:

1. A thermosetting resin comprising a mixture of an epoxidized dienepolymer of a conjugated diene containing 4 to 6 carbon atoms containing0.08 to 0.8 epoxy groups per aliphatic double bond originally present inthe polymer and based on parts by weight of said epoxidized polymer 1 to8 parts of hydrazine and 1 to 10 mols of carbon disulfide per mol ofsaid hydrazine.

2. A thermosetting resin comprising a mixture of an epoxidized dienepolymer of a conjugated diene containing 4 to 6 carbon atoms containing0.08 to 0.8 epoxy groups per aliphatic double bond originally present inthe polymer and based on 100 parts by weight of said epoxidized polymer3 to 6 parts of hydrazine and 1.5 to 3 mols of carbon disulfide per molof said hydrazine.

3. A thermosetting resin comprising a mixture of an epoxidized liquidpolybutadiene containing 0.08 to 0.8 epoxy groups per aliphatic doublebond originally present in the polymer and based on 100 parts by weightof said epoxidized polymer 1 to 8 parts of hydrazine and l to 10 mols ofcarbon disulfide per mol of said hydrazine.

4. A thermosetting resin comprising a mixture of an epoxidized dienepolymer of a conjugated diene containing 4 to 6 carbon atoms containing0.08 to 0.8 epoxy groups per aliphatic double bond originally present inthe polymer and based upon 100 parts by weight of said epoxidizedpolymer 1 to 8 parts of hydrazine, 1 to 10 mols of carbon disulfide permol of said hydrazine, and up to 6 parts of diethylene triamine.

5. A thermosetting resin comprising a mixture of an epoxidized liquidpolybutadiene containing 0.08 to 0.8

epoxy groups per aliphatic double bond originally present and up to 6parts of diethylene triamine.

6.- A thermosetting resin comprising a mixture of epoxidized liquidpolybutadiene containing 3.9 percent by weight of oxirane oxygen and per100 parts by weight of said epoxidized polybutadiene 6.1 parts ofhydrazine and 28.5 parts of carbon disulfide.

7. A thermosetting resin comprising a mixture of epoxidized liquidpolybutadiene containing 3.9 percent by .weight of oxirane oxygen andper 100 parts by weight of said epoxidized polybutadiene 3 parts ofhydrazine and 14.2 parts of carbon disulfide.

8. A method of curing an epoxidized diene polymer of a conjugated dienecontaining 4 to 6 carbon atoms containing 0.08 to 0.8 epoxy groups peraliphatic double bond originally present in the polymer comprisingadding thereto hydrazine and carbon disulfide and heating the resultingmixture at a temperature in the range of 50 to 300 C. until a curedproduct is obtained.

9. The composition produced by the process of claim 8.

10. The method of claim 8 wherein said epoxidized polymer is epoxidizedliquid polybutadiene.

No references cited.

8. A METHOD OF CURING AN EPOXIDIZED DIENE POLYMER OF A CONJUGATED DIENECONTAINING 4 TO 6 CARBON ATOMS CONTAINING 0.08 TO 0.8 EPOXY GROUPS PERALIPHATIC DOUBLE BOND ORIGINALLY PRESENT IN THE POLYMER COMPRISINGADDING THERETO HYDRAZINE AND CARBON DISULFIDE AND HEATING THE RESULTINGMIXTURE AT A TEMPERATURE IN THE RANGE OF 50 TO 300* C. UNTIL A CUREDPRODUCT IS OBTAINED.